Minimal/recommended network latency

[asafshalom]

I am looking for the minimal or recommended network latency issued by Cisco for IP telephony environment. In this case it will probably mean the acceptable latency between the GW and the IP phones itself.

If someone has a reference an official document I will appreciate it

Thanks

[paolo bevilacqua]

The official document would be any of the "voip srnd" - search cco. Anyway voice works fine with g711u and even 250 ms delay, typical as for satellite.

this helps, please rate post if it does!

[asafshalom]

Thanks, i tried looking in the SRND but there is no specific reference to latency numbers.

[paolo bevilacqua · Accepted solution]

E.g. this document:

http://www.cisco.com/en/US/docs/voice_ip_comm/cust_contact/contact_center/customer_voice_portal/srnd/4x/vp40netw.html

maximum specified is 200 ms but even a 20% above that is OK.

When the latency is high and cannot be reduce, just tell users that they cannot expect to be talking at the same time.

[asafshalom]

Thanks, I did find an additional document stating a maximum of 150ms for VoIP telephony environment

[royalblues · Accepted solution]

The value in the document actually mentions the recommended one-way latency to be 150ms

So when you measure it with ping reponse, 300ms should be treated as a threshold.

We have phones in India and the call managers in US, the typical latency is abut 280ms and the phones works fine... We face some issues with quality when the RTD goes beyond 300-310ms

HTH

Narayan